Dovetail Angle Explained
George VondriskaLearn the secrets to creating your joinery with the appropriate dovetail angle. While there are many ways to join two boards together in woodworking joinery, most woodworkers carry a respect and appreciation for the time-honored dovetail joint. It has been long revered for its beauty because of the way that it artfully joins two boards with a compelling display of intricate angles, while at the same time providing an eye-catching effect by the contrasting display of end grain interleaved with long grain. Of perhaps greater importance is the tremendous strength provided by this joint, which is a function of its geometry, with particular emphasis on the dovetail angle. The term “dovetail angle” refers to the slope at which the tails and pins are tapered to form their interlocking bond. It is important to incorporate the correct angle for a given project so that the joint will have maximum strength and durability.
What Are My Options When Choosing a Dovetail Angle?
Most commonly, woodworkers design their joinery using either a 1:6 or 1:8 dovetail angle. If these ratios are new to you, don’t worry, they are explained clearly in this video, along with information on why the angle matters.
When Do I Use Which Angle?
The choice of angle is largely driven by the characteristics of the wood species that is used in the project. The underlying reasoning, along with some guidelines for choosing an appropriate angle for a given situation, is covered in this video.
What Types of Dovetails Does This Apply To?
This video predominately refers to through dovetails, but the concept applies to half-blinds and it applies when you are learning how to make sliding dovetails. When cutting any style of dovetail, it is important to use the correct dovetail angle so that the fruits of your labor will last for generations.
Here's the stuff that's really important to understand about dovetail slope. We talk about this commonly using two different ratios. 1:6, 1:8. One is for softwoods; one is for hardwoods. So, let's have a look at the ratios themselves, what does that mean?
Then let's talk about which is which, what's hardwood, what's softwood, and why that is. So, first off, what are we talking about? We've got 1:6 as one of our commonly used dovetail slopes, 1:8 as the other one. What this is all about is if I draw a line six inches long What this is all about is if I draw a line six inches long and one inch up, and I connect that angle, and one inch up, and I connect that angle, there is a 1:6 dovetail slope. So I'd say you're about to lay out dovetails by hand.
You can draw this on a board, set your bevel square to that angle, and you're good to go. If, on the other hand, I draw a line eight inches long and one inch up, and connect the dots, we have that dovetail slope, which is a shallower angle. 1:8 is a shallower angle because we're going horizontally further before we go up with our one inch. In fact, this is about nine and a half degrees, and this is about 7.1 degrees. and this is about 7.1 degrees.
That's what dovetail slope is. What's the deal, hardwood, softwood? The one on the left, this is our softwood slope. On the right, that's our hardwood slope. Why is that?
It has to do with the compressibility of the fibers. So, let's see if I can draw a dovetail joint here. So looking at end grain, we would have a half pin and then a tail, the other side of the socket, and then probably a full pin. Something like that. There's the tail, except it's probably connected all the way across.
Okay? So, when we talk about this 1:6, 1:8, the smaller the second number, 1:8, 1:6, 1:4, 1:3, 1:8, 1:6, 1:4, 1:3, the smaller that number, the more the angle comes this way. The reason that we use that for softwoods is because of their fiber propensity to compress. So what we're looking at is if I pull on this dovetail in this direction, if I try to pull the tail through the socket in this direction, could these fibers compress to a point where it allows the tail to slip through? By using a 1:6, we have more of a hook holding that in place mechanically.
When we go to a 1:8, this line gets a little closer to vertical. That's okay for hardwoods because the wood tends to be harder, fibers have less chance of compressing. As a result, it's less likely to be able to pull it through. Now, how arcane is this? Well, I think, my guess is that we as woodworkers today probably make a bigger deal out of this than woodworkers did a hundred years ago.
I think a lot of woodworkers who are really good at hand cutting dovetails walk up to the board, they lay the saw in there at an angle, and they start to cut. And they're not splitting hairs over 1:6, 1;8, 1:7, whatever the number is. But, at least if you know the numbers, then you can set your tools as you need to. As you get further along in your dovetail work, don't be afraid to start cutting things by eye because I bet, with a little bit of practice from using these numbers, you're gonna be better by eye than you probably think you are. This will give you a good understanding of dovetail slope and what it's all about, and how to apply that information to your dovetail projects.
I wish you would put subtitles on these videos - sometimes I watch them when watching tv with my wife.
Great Video Thank You George, Some help with dovetail bits for a router and some different jigs would be nice, I bought a Milescraft DovetailTemplateMaster. Made two standard jigs, using mdf, ( I do not like mdf, horrible material to work with ) One Tail Jig, one Pin Jig, They work flawlessly, Just made a Master Copy two templates long, Plan on making more, and longer versions, so I can work on boxes up to 4 to 6 feet long. What I would like to know is, if there is a way to achieve a needlepoint, or houndstooth look, using these jigs. I made the master copy 1 1/4" thick to allow a taller router bit, but not sure if that is going to work with these jigs. The jigs from Milescraft work fine, but the look is very blocky, I may have to go with making them by hand, to get the refined look. Just started practicing, still havent made a working Sliding Tapered Dovetail, I know a couple of mistakes I made, one the narrow side was ( too narrow ) came in too far on each side, the other is cutting the shoulder off, hope to figure this out soon, lol
Why are some dovetail 'pin'? bases made where they are so narrow.. some being 1/8" or less. Would that not make them a lot weaker and compromise the strength of the joint? Are they made that way just for looks?
I have a question concerning another dovetail angle that Veritas has a guide for. It is a 1:14 and from what they say this angle was used way back when and is suitable for both hardwood and softwood from what I gather. I have a Porter Cable 4216 dovetail jig that I don't use because from my experience it is a PITA and I am leaning toward trying to cut my dovetails by hand. I also prefer a more pronounced angle for the dovetail and not all that concerned about exact spacing. All I build is small boxes and clocks so the holding power is minimal at best. Just some thoughts about dovetails that is very seldom covered.